Published in Nature Health, the study was conducted by a multidisciplinary team of experts, including Dr. Menelas Nkeshimana, the Head of the Health Workforce Development Department at the Ministry of Health, alongside researchers from the Rwanda Biomedical Centre (RBC), the University of Rwanda, King Faisal Hospital, and other institutions.
While filoviruses such as Ebola and Marburg were already known to persist in certain body fluids after recovery, sexual transmission of Marburg had not been clearly documented in previous outbreaks across Africa. The new findings therefore, add important evidence to the understanding of viral persistence and post-recovery transmission risks.
Confirmed post-recovery transmission events
The study describes two separate transmission events in which recovered male patients, later confirmed to have viral remnants in semen, transmitted the infection to female partners through unprotected sexual contact.
Both men had previously been treated for Marburg and discharged after meeting clinical recovery criteria, including two consecutive negative blood tests taken 24 to 48 hours apart. No semen testing had been conducted at the time of discharge.
Shortly after discharge, both individuals engaged in unprotected sexual intercourse, after which both female partners developed symptoms consistent with Marburg infection and later tested positive.
Case A1 and Case A2
The first case involved a 25-year-old man (Case A1) who was infected between 8 and 15 September 2024 and developed symptoms on September 25, including fever, vomiting, nausea, diarrhoea, fatigue, and muscle and joint pain.
He was admitted to hospital on September 27 and tested positive for Marburg on September 28. He received treatment, including remdesivir, and was discharged on October 10, 2024, after clinical recovery and two negative blood tests.
Nine days after discharge, on October 19, 2024, he had unprotected sexual intercourse with a 21-year-old woman (Case A2). The woman developed symptoms on October 24 and was admitted to hospital on October 27. She tested positive for Marburg on October 29 and received treatment before being discharged on November 8, 2024.
Investigators found no alternative exposure to the virus apart from the post-discharge sexual contact.
Case B1 and Case B2
The second transmission event involved a 29-year-old man (Case B1) infected on September 23, 2024, who developed symptoms on September 30 and was admitted to hospital on 1 October after testing positive for Marburg.
He received treatment with remdesivir and showed clinical improvement. He was discharged on 15 October 2024 after two consecutive negative blood tests.
On October 19, 2024, he had unprotected sexual intercourse with a 29-year-old woman (Case B2). She developed symptoms on October 23, was admitted on October 25, and tested positive for Marburg on October 26. She was treated and discharged on November 5, 2024.
As with the first cluster, investigators did not identify any other plausible exposure route, making post-recovery sexual transmission the most likely explanation.
Laboratory and genomic findings
The research team conducted epidemiological investigations alongside partial genomic sequencing of viral samples. Although full genome recovery was not possible, sufficient genetic material was obtained to support outbreak linkage.
In Case A1, 71% of the viral genome was recovered, while in Case B2, 76% was recovered. The sequences were classified within Marburg clade B and showed close relation to strains previously identified in the Democratic Republic of Congo (1999–2000) and Uganda (2007–2009).
The sequences were labeled PZ112888 and PZ112889, and comparison with other outbreak data from Rwanda indicated strong genetic similarity, supporting a linked transmission chain.
Study limitations and public health implications
The researchers noted several limitations, including the inability to perform full viral sequencing and the lack of virus culture from semen samples due to limited laboratory capacity.
Importantly, no semen testing was performed before hospital discharge under earlier protocols, which relied solely on blood tests confirming the absence of detectable virus.
The researchers noted that these findings alter our understanding of post-recovery risks, stating: “While the persistence of filoviruses in immune-privileged sites like the testes has been documented, these findings provide definitive genomic and epidemiological confirmation of Marburg virus sexual transmission from recovered individuals. This underscores an urgent need to re-evaluate global discharge criteria…”
Following these findings, Rwanda revised its post-recovery monitoring guidelines for Marburg. New protocols now include testing of semen and other body fluids at defined intervals after recovery, as well as extended follow-up of survivors to better assess viral persistence and transmission risk.
Rwanda’s first-ever Marburg Virus Disease (MVD) outbreak was officially declared on September 27, 2024. Epidemiological investigations traced the origin of the outbreak to a zoonotic spillover event at a mining cave inhabited by Egyptian fruit bats (Rousettus aegyptiacus).
The index case, a 27-year-old miner who worked at the site, was subsequently admitted to King Faisal Hospital in Kigali, where the highly contagious virus quickly spread to healthcare workers.
Ultimately, approximately 78% of all confirmed cases involved clinical staff across two medical facilities in Kigali. While infections were detected in seven of Rwanda’s 30 districts, the highest concentration remained heavily localised within the three districts of Kigali City: Gasabo, Kicukiro, and Nyarugenge.
The outbreak resulted in 66 confirmed cases, 15 deaths, and 51 recoveries. In adherence to World Health Organisation (WHO) guidelines, the Government of Rwanda officially declared the end of the outbreak on December 20, 2024, marking 42 consecutive days, representing two full incubation periods, with zero new confirmed cases.

















































































































